The objective of the proposed research is to synthesize tubulin in an in vitro system comprising chromatin, RNA polymerase, ribosomal subunits, initiation factors, elongation factors, termination factors, aminoacyl-tRNA synthetases, and tRNA. Chromatin will be isolated from chick embryo cerebra, and the other components will be isolated from rabbit reticulocytes, rat liver, and chick embryo cerebra. We will use anti-tubulin to isolate chick embryo cerebral tubulin mRNA. In vitro synthesized tubulin will be assayed by adding purified tubulin to the reaction mixture and running through several cycles of polymerization-depolymerization of microtubules. We also plan on studying the function of the two proteins tightly bound to messenger RNA. We will isolate nuclear informosomes and polysomal messenger ribonucleoproteins in Renografin gradients and study their binding of the two tightly bound proteins.